Well drill



April 22, 1941. l.. w. KRALL. 2,239,106

lv 3, '3l

v 42. 30 CU. Knall,

4 33 /9 w INVENTOR. A* A BY gw!" @w/q E E i: :tE E

ATTORNEY April I22, 1941. L, w, KRALL WELL DRILL Filed Jan. 28, 1939 2Sheets-Sheet 2 5&0 w Kfm/cd2.

INVENTOR.

ATroRNEYs Patented Apr. 22, 1941 WELL DRILL ngo w.

Krall, Houston, Tex., assignor of one-half to W. M. Mercer, Houston,Tex.

Application January 2s, 1939, serial No. 253,266

4 Claims.

My invention relatesn to well drills such as are employed in drillingdeep wells for water, oil, sulphur and the like. It pertains moreparticularly to drag bits of the fish tailtype whereby the cutting isperformed by scraping blades.

It is an object of the invention to provide a removable shoe or plate tobe secured on the forward end of the bit and to which the cutting bladesare secured.

It is a further object of the invention to provide a connection betweenthe removable cutting portion of the bit and the head upon which it ismounted which will 'permitthe parts to be secured together firmly with aminimum of diiiiculty.

It is a further object to provide means for preventing removal of thecutting portion from the head which can not be detached or loosened inthe operation of the drill.

A further object of the invention is to provide a connection between thecutting blades and the head of the bit which will remain in tightengagement and in which the spreading of fthe head relative to theblades is prevented.

It is also an object bf the invention to provide a wedging fit betweenthe blade and the head which will remain in tight engagement during theoperation of the device. y

It is a further object of the invention to provide an indicator in thehead of the drill which will operate to give an indication to theoperator at the surface when the cutting blades have been worn so. thatthe gauge of the well will not be materially reduced.

It is desired to form an indicator which will influence the flow offlushing fluid through' the drill in response to the wearing down lofthe cutting portion of the head to a critical point.

It is a further object of the invention to provide a core drill to beemployed with the well drill previously referred to which may be moved(Ci. Z55-61) giiidixient of the invention from that disclosed in S. Fig.4 isa. side elevation of the drill disclosed in Fig. 3. 5 Fig. 5 is acentral longitudinal section forward into the formation in response tothe pressure cf flushing fluid in the drill stem.

It is a, further object of the invention to provide means for closingthe passage into which the core bit is inserted during the period whenthe core bit is not in operation. l

Referring to the drawings herewith, Fig. l is a bottom plan view of adrill bit embodying the inventionVa certain portionof the cuttingelement being broken away for purposes of clearness.

Fig. 2 is a similar view taken in side elevation with certain partsbeing broken away.

Fig. 3 is a bottom plan view of atdifierent emthrough a drill collar anddrill with my improved core barrel shown. therewith, certain parts ofthe structure ,being shown in elevation.

Fig. 6 is a view similar to that disclosed in Fig. 5 but showing the useof a bit plug in place of the core barrel.

Fig. 7 is a transverse section taken on the plane 1-1 of Fig. 12.

Fig. 8 is a. similar view taken on the plane 8-8 of Fig. 10.

Fig. 9 is a perspective view of the cutting blade to be employed withthe embodiment of the drill shown in Figs. 3 and 4-and with certainparts shown in section.

Fig. 10 is a side view partly in section showing one form of indicatorwhich may be employed in signaling to the operator when the drill hasbecome worn.

Fig. 11 is a perspective view of the cutting blade employed with theheady disclosed in Figs. 5 and 6.

Fig. l2 is a side view partly in central vertical section indicating asecond form of indicator to signal to the operator when the cuttingblades have become worn suiiiciently to necessitate withdrawal of thebit.

Fig. 13 is a perspective view showing the structure of the head employedwith the cutting element disclosed in Fig. 2.

With reference'to the drill bit disclosed in Figs. 1, 2, 11 and v13, Ihave shown a head i'which has a threaded socket 2 for connection withthe drill collar or tool joint 3. The lower end of the head is flattenedoff on the plane indicated at 4 and is provided with a tenon 5projecting therefrom to lengage with the cutting element. With referenceparticularly to Fig. 13 thistenon 5 is extended around the lower portionof the bit in the arc of a circle, said tenori decreasing in widthtoward the advancing end 6 thereof,

Aas it is screwed or inserted into the cutting porcuttings and theflushing fluid. 'Ihe blade sup-4 porting portion is formed upon twoforward projections having 'the mortises thereon as previously referredto.

The cutting element, shown in Fig. 1l, .is

` shaped to engage with the forward end of the a shown at 9 throughwhich the core drill may be inserted. Each half of the cutting elementhas a mortise III cut therein grooved to engage over the tenon on thehead and dovetailedas shown in Fig. 1l so that it may be mounted `vonthe head by a screw or rotative movement over the tenons 5 which arereceived within the mortises I0. The mortises also are formed with wallsconverging inwardly, the inner end of each mortise being closed by awall at II. 'I'hus it will be understood that the blade may be mountedon the head by inserting the mortise IIII over the tenon 5 on the headand by a partial rotation the tenon will be wedged in the mortise sothat it will fit securely in position when the forward end of the tenonhas engaged the wall I0.

Openings are provided through the mortise and tenon connection toreceive screws or bolts through which the parts'are held in position.Thus openings I2 in the mortises and I5 in the tenons are arranged toreceive screws I4 whereby an unscrewing movement of the cutter on thehead is prevented. At the other end of the tenon is an opening I3through which iiushing iluid from the head may be discharged upon theformation. Said openings I3 will register with similar openings I6 inthe cutting element and will issue, as shown at I6 in Fig. 1, in thedownward direction.

Additional openings for the discharge of ilushing fluid are rformed inthe lower tapered portion of the head at I1. There are two of theseopenings one on each side and Yit will be understood from Fig. 2 thatthese openings connect upward- 1y into the passage I8 through which theflushing :duid passes.

lAttention is directed to the manner in which the screws Il' are mountedin position to hold the cutter head assembled upon the drill head. vInFig. 2'it will'be understood that the inner threaded portion I4 of eachscrew is'extended into the head of the bit leaving an outer unthreadedportion Mb. The diameter of the screw is reduced to form an outerprojection I3 thereon which engages through the opening in the cutterhead. When this screw is to be loosened itis screwed downwardly in theopenings I2 and I6 so that the projection I4c is moved inwardly beyondthe dividing line between the drill head and the cutter member. Thiswill enable the cutting element to be rotated and removed from the headand a new cutting element inserted in position. The screw driver is theninserted to engage in the end of the screw and the screw is unscrewedfrom its seat so as to bring the reduced portion Mc back into the recessin the cutting portion. In this manner it is impossible to lose thescrew from the drill head during operations and I am still enabled tosecurely lock the parts together. As will be seen in Figs. 1 and 2 theshoe having the blades thereon may be formed in a single member whichmay be xed upon the head in the manner described or the cutting elementmay be formed in two parts as shown in Fig. 1l. In such cases at eachside of the shoe or cutting element are forwardly directed cutting edgesI9 and I9. It will be seen that when the cutting blades are worn down toyapproximately the level of the forward face of the cutting shoe, asindicated at 20. the drill will not progress any further and anindication will be given to the driller that the blades have becomedulled and that it is time to remove the bit from the hole.

In Figs. 3 and 4 the blade which is employed is not formed upon acutting shoe as in the previous embodiment but the blades are preferablyformed in one piece and adapted to be inserted upwardly into a slot inthe head. As will be seen from Fig. 4 the cutting blade 2l is formedwith forward cutting edges I9 as in the Previous embodiment but theupper end of the blade is formed to be inserted into a slot in the head.This blade has at each sident the head a laterally extending tenon 22.Said tenon has a flat inclined surface 23 inclined toward the innerportion of the head. The lateral face of the tenon is steppedbackwardly, as shown at 24 in Fig. 3, to engage a shoulder on the head.The blade thus formed is indicated in Fig. 9 wherein the tenon 22 isshown projecting from the outer edge of the blade I3'. This tenon, whichis in effect a compound tenon, tapers from the lower end adjacent theblades I9'IL in an upward direction, as will be noted along the plane 23in Fig. 9. Thus the tenon may be inserted into a complementary mortisein the head and will wedge upwardly in position as it is inserted intothe head. When wedged tightly, there is a transverse opening 25 throughthe blade which will register with a transverse opening 26 in the head.This opening through the head is tapered as shown at 21 in Fig-4 toreceive a pin driven therein, thus locking the blade firmly in position.This pin, as seen particularly in Fig. 3, is not extended entirelythrough the head when wedged in position but it will be possible toinsert a driftpin into the smaller end of the opening at 23 to drive thepin from its seat when the blade is to be again removed. There is arecess 29 in the head adjacent the upper end of the blade which makes itpossible to exert pressure ori the upper end of the bladeto remove itfrom its seat when the pin4 has been withdrawn.

This blade operates as does the previous embodiment to stop the advanceof the bit when the cutting blades have been worn to a point near thelower end of the bit head. Said lower en'd being flattened oi will notadvance afterl the"- blades have been suiilciently worn and will give anindication to the operator that the bit may be withdrawn.

.A core bit may be employed with myv type o! bit, as shown in Fig. 5. Inthis type of bit there is a passage centrally through the bit head Ilthrough which a core barrel 30 may pass. I further provide a bushing 3|,which is screwed within a recess 32 on the inner portion of the head.Said bushing is provided with longitudinal grooves which are adapted tore'ceive longitudinal ridges or splines 33 upon the core barrel.

Above the end of the bit is a drill collar or sub 34, which is securedat its upper end to the tool joint or drill stem 35. 'I'here is alongitudinal passage 36 through the drill collar through which the corebarrel may be inserted. Adjacent the upper end of the passage 36 is arecess 31 formed by enlarging the passage to provide a chamber or spaceinto which the latching members on the plug bit may engage. Said plugbit will be later described. The core barrel has a threaded engagementad- Jacent its upper end with a head 38. Said head has in its outerperiphery a packing ring 39 of rubber or similar packing material whichengages tightly against the inner wall of the drill collar. This headcloses the upper end of the barrel and has an upper extension 40 whichis serrated to provide engagement for an overshot or grab member 4I.

In Fig. 6 I have shown how the opening through the drill bit may beclosed when the core barrel is not being employed. Inl this -devicethere is a small bit or cutting member 42 which iits.

l a shoulder 41 within the recess 31 thus holding the plug bit inposition during the drilling operation.

sleeve 48 which iits over the upperend of the rod and has a lateral slot49 therein to allow the outward movement therethrough of the latchingdog 45. This sleeve has a ltransverse pin 50 which engages within a,slot i in the rod, thus allowing the sleeve a limited longitudinalmovement relative to the rod. At the upper end of the sleeve is aserrated head 52 to be engaged by the overshot which may be employed.

In the operation of the device the plug bit may be dropped downwardlythrough the drill stem to engage within the bushing 3l, a packing member53 thereon forming a seal with the upper tapered end of the bushing. Inthis position the sleeve 4'8 will drop downwardly and allow the latchingdog to move outwardly away from its retracted position and engageagainst the shoulder 41. When it is desired to remove the plug, however,a grab or overshot, such as is shown at 4i (Fig. 5), may be lowered intothe well with a cable 54 to engage the extension 52 and thus pullupwardly upon the sleeve 48 and withdraw the latch dog 45 and thusenable the plug bit to be removed upwardly to the surface.

The core barrel then may be dropped downwardly into position projectingthrough the opening in the drill head. The Vupper end of the core barrelwill then extend upwardly into the drill collar and will close thevpassage therethrough of flushing fluid. The drill bit may be vsuspendedfrom the surface slightly oii? the bottom oi the hole and the drillstem-may be then rotated and the pressure of the flushing iiuld exertedupon the upper end of the core barrel will force it downwardly intotheformation as the drill stem is rotated until finally the head 38 willmove into the recess 55 in the drill, head.

VIn this position the flushing fluid may pass around the head 38 andoutwardly in the channels around the core barrel and an indication willbe given to the operator that it is time to withdraw the core barrel andthe core therein from the well.

, In Figs. '1, 8, l0 and 12 I have disclosed other forms of indicatorswhich may be employed to show when the blades of the cutting member havebeen worn sufficiently to warrant the drill bit being removed from thewell. In Figs. 'l and 12, the indicator includes .a central shaft 56which has at its lower end a reduced section 51 which projects throughan opening, such as is shown at 9 in Fig. 11, so as to extend approxi-There is a latch control member formed by a mately on a level with theblades I9b of the bit. The forward end is formed with cutting members 58which act to cut the small portion at the' center of the hole. The shaft56 extends upwardly and a bearing member 59 is formed thereon to iitwithin a sleeve 60 formed within a spider'or supporting member BI in thesub 62.

It will be noted that in this case the drillhead lb is formed with asocket to receive the lower threaded end oi the sub 62 and that theshaft 56 projects from the head upwardly into the interior chamber inthe sub. The spider in which the shaft bearing 59 is journaled is shownin Fig. 7 as having three sector shaped arms 63 thereon with similarshaped openings 64 between them, the said openings formi-ng a passagefor the flushing iiuid. Below the spider 6| I form upon the shaft 3sector shaped arms 65 which are held normally out of registration withthe opening 54 by means of a spring '66, one end of which is mountedwithin a slot 61 in the end of the bearing member and the otherend ofwhich is iixed within the spider. This spring serves-to exert a torqueupon the bearing member 59 -moving the arms in a direction to bring apin 68 upon one of the arms 65 into a .recess 69 in the spider, as shownin Fig. 7.

In the rotation of the bit the engagement of the points 58 upon theshaft 56 tends to rotate the said shaft to move the pin 68 out of therecess 69. This rotation of the shaft 56 is prevented, however, by a pin10, which is extended through an opening in theblade i9b in a radialdirection so that Ithe inner end oi' the said pinshaft 56 will move thepin 16 outwardly in the opening so as to allow the shaft 56 to rotate.

Thus when the bit has been worn sufficiently to warrant` removal of thebit from the hole the operator will note that the pressure fluid ischoked downwardly so as to throttle .the pumps. This will beaccomplished because of the rotation of the shaft 56 as soon as thelatch pin is allowed to move outwardly, thus bringing the sector shapedarm into position to close the opening 64 and choke off the flow offlushing fluid.

In Figs. 8 and 10 I have a similar construction but in the head of thedrill bit I have a valve member 13 which is pivoted at its two ends uponpins 14 which are extended through the Wall of the head and tted withinrecesses in the end of the valve member. This will be understood fromFig. 8. The valve is thus pivoted for rotation in the head. It isnormally held against rotation by a latch pin 15, which is extendedupwardly through an opening 16l in the blade and the head of the bit sothat the notched end 11 `thereon will engage with one edge of the valvemember.

'I'his pin 15 is held in the passage 15 by a soft metal plug 18, whichis in turn held in place by of latching position. It will be understoodthat due to the position of the valve member 13 there will be a.pressure exerted upon the valve by the flushing fluid to cause it torotate from that position, and such pressure will be sufficient to movethe pin 15 as soon as the lower end of the bit is worn sufliciently toallow the pin to slide downwardly and outwardly. As soon as the valve I3is allowed to rotate it will close the passage for fluid through thehead, or at least cause a rotation of the valve, which will interferewith the passage of uid, and thus indicate to the operatorf-that the bithas b een sufficiently Worn to warrant its removal from the well.

It will be understood that I havethus provided a drill bit which has aneasily removable cutting end thereon and in which the entire cuttingsurface subjected to wear may be removed from the head of the bit and anew similar cutting end mounted thereon and the drilling continued. Thehead of the drill will itself sustain but little wear and the drill maythus be operated with economy and the changes in the cutting elementupon the head may be made with the consumption of the minimum of time.

It will also be seen that I have provided an indicator which will give asignal to the operator at the surface when it is desirable to withdrawthe bit from the hole to replace the cutting element.

The advantages of my core barrel which has been described reside-in thefact that the core may be cut without the operation ofthe main drill,thus enabling an uncontaminated core to be obtained. The core barrel isdriven into the formation entirely by the force of the flushing fluidduring a period when the main drill bit is not advancing. This is afeature of importance in obtaining a core uncontaminated. by theflushing fluid and retaining the original composition of the corewithout contamination.

What is claimed is:

1. A drill head, cutters thereon, a passage for flushing fluid throughsaid head, a valve plate mounted transversely of said passage andpivoted to rotate therein, means engaging said plate to hold it in openposition, said holding means being releasable in response to apredetermined amount of wear upon said cutters, whereupon said valveplate may be moved by said flushing fluid to partially close saidpassage.

2. A Well drill including a head, cutters on the forward end thereof, amember adapted to be worn as the cutters are worn, a passage throughsaid head for flushing fluid, and means in said passage acted upon bythe fluid therein to close off the flow of fluid through said head whensaid member is worn a predetermined amount.

3. A well drill including a head, cutters on the forward end thereof, apassage for flushing fluid in said head, an indicator channel from saidpassage to one of said cutters, `a plug ln said channel andfluid-operated means in said pasvsage acting in response to apredetermined wear upon said plug to close oif said passage.

4. A well drill including a head, cutters at the forward end thereof, afluid passage in said head, a closure for said passage and meansnormally holding said closure in open position but operating in responset0 a predetermined Wear upon one of said cutters to release said holdingmeans and permit said closure means to cheek the flow of fiuidvin saidhead.

LEO W. KRALL.

